1. Field of the Invention 
This invention relates to methods for visualization of the coronary arteries which supply blood to the heart. 
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98. 
The arteries which supply blood to the heart itself are termed “coronary” because they encircle the heart like a crown. These arteries handle 5% of the blood flow in the body and coronary artery disease is a leading cause of death. The arteries which encircle the heart have extensive bifurcation or branching and supply blood to every portion of the heart. This mass of interwoven arteries has been described as forming a labyrinth web or as resembling the roots of a tree. Therapeutic intervention in coronary artery disease, however, may require unambiguous identification of the coronary arteries. This task is complicated by the fact that the angiograms, which allow visualization of the arteries, portray them in stark contrast while the heart itself appears indistinct and  shadowy. This patent application discloses a method of analysis of angiograms, applicable to recorded or real time angiograms, which facilitates unambiguous identification of the coronary arteries. 
In particular, the slight rotation of the heart (twist) which accompanies a heartbeat is exploited to provide the angular offset of two images which allows the generation of a stereoscopic view using a single, non-moving image collector. Use of this process in connection with conventional angiograms allows examination of the coronary arteries and definitive determination of the position of each artery with respect to the heart, particularly which arteries are in front and which are behind the myocardium Use of this method results in substantial reduction of time required to correctly interpret coronary angiograms. 
A study of the movements of the beating human hearts of 10 healthy volunteers has provided details of this phenomenon, termed “cardiac twist”. During isovolumetric contraction, all ventricular twist was counterclockwise. Later in systole, the basal segments changed direction and rotated in a clockwise direction, whereas the apical segments continued counterclockwise rotation. The mean short axis net ventricular twist (apex-base) at 80% systole was 12.6±1.5 degrees. The four wall segments were heterogeneous in twist with lateral wall at 20.6±1.7 degrees; anterior wall, 17.5±5.1 degrees; inferior wall, 8.8±1.5 degrees, septum 3.5±2.4 degrees. The twist between anterior and lateral walls was significantly different from the other walls. It was concluded that twist was a robust parameter of myocardial function. Lorenz, C. H., Pastorek, J. S., and Bundy, J. M. Delineation of Normal Human Left Ventricular Twist  Throughout Systole Tagged Cine Magnetic Resonance Imaging. Journal of Cardiovascular Magnetic Resonance, Vol. 2, issue 2 (2000), pp. 97-98. 
Current angiogram examination of patients involves the injection of an x-ray opaque dye into an artery, followed by the recording of an x-ray angiogram which shows the arteries in stark contrast. A recorded angiogram is similar to a motion picture with individual pictures or frames taken at from 10 to 100 frames per second. The procedure involves repeated injections and recording after slight repositioning of the detector between injections. This is because of the need to unambiguously identify arteries despite the fact that a single angiogram does not allow distinguishing between arteries on the front and the back of the heart. By recording repeated angiograms from different angles, the coronary arteries can be identified. The process, however, involves intensive study of recorded angiograms by skilled specialists and the study of one set of angiograms may require several specialists and one half hour of time. 
Stereoscopic three-dimension images are a mental construct created by the essentially simultaneous viewing of separate images of a three-dimensional object by the left and right eyes. The separate images of the same scene differ by an angular offset which corresponds to the fact that the viewer's eyes are offset horizontally. This offset, also termed “binocular disparity” corresponds to the slightly different views of a three-dimension object seen by the left and right eyes. In this invention cardiac twist is used to provide the offset which allows the stereoscopic viewing of cardiogram images and facilitates the identification of cardiac arteries. 
U.S. Pat. No. 4,181,839 discloses a collimator which simultaneously provides two separate views of an internal organ, especially a heart. Images are created  by the radioactive decay of injected labeled materials which are detected by an Anger or fluoroscope scintillation camera. The offset required for stereoscopic images are obtained by taking views at two different angles, such as 45° and 135° or 60° and 120° etc. and there is no need to move camera or patient. The views may be used to provide multiple images for stereoscopic three-dimension views of an organ. 
U.S. Pat. No. 5,233,639 discloses a stereoscopic fluoroscope and method of producing stereoscopic X-ray images. This involves an X-ray source and image intensifies which are rotated at the same angular velocity in order to obtain the offset required for the stereoscopic viewing. 
U.S. Pat. No. 5,503,152 discloses an ultrasonic transducer with parallel arrays of transducer elements used to simultaneously view an organ, the spacing of the multiple elements used to provide the offset required for a stereoscopic display. 
U.S. Pat. No. 5,601,084 discloses an ultrasonic imaging data transesophageal probe which images the end of the systole and end of the diastole portions of the cardiac cycle. The data are analyzed and provide information on the pumping volume and thickness of cardiac wall. The probe is used to obtain a variety of displaced images. The offset required for stereoscopic viewing is obtained by moving the probe with respect to the heart. 
U.S. Pat. No. 5,687,737 discloses an electrophysiological mapping system which covers the external or internal surface of the heart with an array of electrodes. A sock with attached electrodes is stretched over the outside of the heart or a balloon with attached electrodes is inserted into a ventricular cavity and inflated. The data are displayed on a three-dimension image which is generated by a program which integrates  the multi-electrode data and generates an image. The generated image is not a stereoscopic image. 
U.S. Pat. No. 5,730,129 discloses a device with an internal probe whose position is monitored by magnetic resonance or through radio-frequency. The internal probe is inserted into a body cavity and an external ultrasonic probe which is attached to the outer surface of the patient. The use of the external probe allows the operator to orient the location of the internal probe despite movement of the organ or of the patient. 
U.S. Pat. No. 6,027,451 discloses an apparatus with a first ultrasonic transducer attached to a catheter and attached to a data processing device and a second ultrasonic transducer which is attached to the external surface of the body. This allows orientation of the image from the first transducer despite rotation of the transducer on insertion and despite movement of the heart and the lungs. 
U.S. Pat. No. 6,398,736 discloses an ultrasonic catheter for insertion into the large vessels of the heart. Images are displayed in which collects images in 2d, 3d, 4d  and higher dimensions through parametric expression of flow. Doppler ultrasound displays blood flow in three-dimension images which are not stereoscopic images. 
The discovered prior art inventions do not disclose the present invention. In particular, the prior art methods involve acquiring stereoscopic displacement or offset through relative movement of a single detector, or through the use of multiple detectors. The present invention exploits the natural slight rotational movement about the vertical axis of the heart associated with the heartbeat to provide the stereoscopic displacement necessary for stereoscopic visualization. Such stereoscopic visualization facilitates unambiguous determination of the identity and location of coronary arteries.  